Spring Securtiy 认证流程(源码分析)

当用 Spring Security 框架进行认证时，你可能会遇到这样的问题：

你输入的用户名或密码不管是空还是错误，它的错误信息都是 Bad credentials。

那么如果你想根据不同的情况给出相应的错误提示该怎么办呢？

这个时候我们只有了解 Spring Securiy 认证的流程才能知道如何修改代码。

好啦，来看下面的例子，大部分人的 WebSecurityConfig 的 configure 代码都类似于下：

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        // TODO Auto-generated method stub
        http
        .authorizeRequests()
        .anyRequest().permitAll()
        .and()
        .formLogin().loginPage("/signin")
        .usernameParameter("username")
        .passwordParameter("password")
        .loginProcessingUrl("/signin")
        .and()
        .csrf().disable();
    }

相信以上代码大家都知道什么意思：任何请求信息都允许，也就是不需要身份认证。

登录页面请求为 /signin，用户名和密码参数的name属性分别是 username，password。登录页面 form 的 action 请求为 /signin。

当然这个 action 不必和登录页面请求一样。最后的那个是禁止跨站请求伪造。

这段代码和登录认证联系较大的应该是从 loginPage() 到 loginProcessingUrl() 里的方法。

咱先从 loginPage 看起，鼠标左键拖动覆盖 loginPage，然后右键 Open Declaration 就进入到了 FormLoginConfigurer 类。

这个类里值得注意的方法有两个：构造方法和 loginPage 方法。

    public FormLoginConfigurer() {
        super(new UsernamePasswordAuthenticationFilter(), null);
        usernameParameter("username");
        passwordParameter("password");
    }

    public FormLoginConfigurer<H> loginPage(String loginPage) {
        return super.loginPage(loginPage);
    }

构造方法中使用了一个用户名密码认证过滤器类，这一看就和认证有关系。

loginPage 方法大家可以自行按照这个步骤查看，现在直接看 UsernamePasswordAuthenticationFilter 类。

    public static final String SPRING_SECURITY_FORM_USERNAME_KEY = "username";
    public static final String SPRING_SECURITY_FORM_PASSWORD_KEY = "password";
    private String usernameParameter = SPRING_SECURITY_FORM_USERNAME_KEY;
    private String passwordParameter = SPRING_SECURITY_FORM_PASSWORD_KEY;
    private boolean postOnly = true;

　　 public UsernamePasswordAuthenticationFilter() {
        super(new AntPathRequestMatcher("/login", "POST"));
    }

　　 public Authentication attemptAuthentication(HttpServletRequest request,
            HttpServletResponse response) throws AuthenticationException {
        if (postOnly && !request.getMethod().equals("POST")) {
            throw new AuthenticationServiceException(
                    "Authentication method not supported: " + request.getMethod());
        }
        String username = obtainUsername(request);
        String password = obtainPassword(request);
        if (username == null) {
            username = "";
        }
        if (password == null) {
            password = "";
        }
        username = username.trim();
        UsernamePasswordAuthenticationToken authRequest = new UsernamePasswordAuthenticationToken(
　　　　　　　　username, password);
　　　　 setDetails(request, authRequest);
        return this.getAuthenticationManager().authenticate(authRequest);
    }

这只是其中一部分代码，其他的可以自己看。该类中定义的两个字符串和构造方法定义了默认的登录方式。

登录 action 请求为以 POST 方式的 /login，用户名及密码分别以 username，password 属性值获取。

该类的父类的父类 GenericFilterBean 实现了 InitializingBean 接口，也就是会初始化为一个 Bean。

当看到 attemptAuthentication 时，就知道他是认证的方法啦。

这里咱直接看到 new UsernamePasswordAuthenticationToken(username, password);

    public UsernamePasswordAuthenticationToken(Object principal, Object credentials) {
        super(null);
        this.principal = principal;
        this.credentials = credentials;
        setAuthenticated(false);
    }

从这里可以知道，它把用户名和密码分别存在了 principal，credentials 里。

现在我们只需要记住登录信息存在了 authRequest 里。现在来看下setDetails，虽然我不感兴趣。

    protected void setDetails(HttpServletRequest request,
            UsernamePasswordAuthenticationToken authRequest) {
        authRequest.setDetails(authenticationDetailsSource.buildDetails(request));
    }

它调用了一个 buildDetails 方法，实际上是调用的：(追根溯源可以看到)

/**
  * Records the remote address and will also set the session Id if a session already
  * exists (it won't create one).
  *
  * @param request that the authentication request was received from
  */
public WebAuthenticationDetails(HttpServletRequest request) {
        this.remoteAddress = request.getRemoteAddr();

        HttpSession session = request.getSession(false);
        this.sessionId = (session != null) ? session.getId() : null;
    }

从源码注释可以看到，它是记录远程地址并且会设置一个会话 ID，这里我们不管它了。

直接看这一句：return this.getAuthenticationManager().authenticate(authRequest);

它调用的是一个实现了 AuthenticationManager 接口的类的 authenticate 方法。

从源码中我们找不到它用的是哪个实现类，网上说是 ProviderManager 类，我们来看一下该类。

public class ProviderManager implements AuthenticationManager, MessageSourceAware,
        InitializingBean {
　　public Authentication authenticate(Authentication authentication)
            throws AuthenticationException {
        Class<? extends Authentication> toTest = authentication.getClass();
        AuthenticationException lastException = null;
        AuthenticationException parentException = null;
        Authentication result = null;
        Authentication parentResult = null;
        boolean debug = logger.isDebugEnabled();

        for (AuthenticationProvider provider : getProviders()) {
            if (!provider.supports(toTest)) {
                continue;
            }

            if (debug) {
                logger.debug("Authentication attempt using "
                        + provider.getClass().getName());
            }

            try {
                result = provider.authenticate(authentication);

                if (result != null) {
                    copyDetails(authentication, result);
                    break;
                }
            }
            catch (AccountStatusException e) {
                prepareException(e, authentication);
                // SEC-546: Avoid polling additional providers if auth failure is due to
                // invalid account status
                throw e;
            }
            catch (InternalAuthenticationServiceException e) {
                prepareException(e, authentication);
                throw e;
            }
            catch (AuthenticationException e) {
                lastException = e;
            }
        }

        if (result == null && parent != null) {
            // Allow the parent to try.
            try {
                result = parentResult = parent.authenticate(authentication);
            }
            catch (ProviderNotFoundException e) {
                // ignore as we will throw below if no other exception occurred prior to
                // calling parent and the parent
                // may throw ProviderNotFound even though a provider in the child already
                // handled the request
            }
            catch (AuthenticationException e) {
                lastException = parentException = e;
            }
        }

        if (result != null) {
            if (eraseCredentialsAfterAuthentication
                    && (result instanceof CredentialsContainer)) {
                // Authentication is complete. Remove credentials and other secret data
                // from authentication
                ((CredentialsContainer) result).eraseCredentials();
            }

            // If the parent AuthenticationManager was attempted and successful than it will publish an AuthenticationSuccessEvent
            // This check prevents a duplicate AuthenticationSuccessEvent if the parent AuthenticationManager already published it
            if (parentResult == null) {
                eventPublisher.publishAuthenticationSuccess(result);
            }
            return result;
        }

        // Parent was null, or didn't authenticate (or throw an exception).

        if (lastException == null) {
            lastException = new ProviderNotFoundException(messages.getMessage(
                    "ProviderManager.providerNotFound",
                    new Object[] { toTest.getName() },
                    "No AuthenticationProvider found for {0}"));
        }

        // If the parent AuthenticationManager was attempted and failed than it will publish an AbstractAuthenticationFailureEvent
        // This check prevents a duplicate AbstractAuthenticationFailureEvent if the parent AuthenticationManager already published it
        if (parentException == null) {
            prepareException(lastException, authentication);
        }

        throw lastException;
    }
}

这里我只给出该类的声明和 authenticate 方法，从类的声明可以看出来它也会初始化为一个 Bean，咱找不到很正常对吧。

authenticate 方法会遍历所有的 AuthenticationProvider ，然后调用 provider 的 authenticate 方法。

如果认证结果不为空的话将会保存到 result 中，并且擦除认证信息再返回 result。

为空的话一般是没有提供 AuthenticationProvider，会报 ProviderNotFoundException 错误。

现在我们来看下 provider 的 authenticate 方法。

    @Bean
    public AuthenticationProvider authenticationProvider() {
        DaoAuthenticationProvider provider = new CustomAuthenticationProvider();
        provider.setMessageSource(messageSource);
        provider.setUserDetailsService(userService);
        provider.setPasswordEncoder(new BCryptPasswordEncoder());
        return provider;
    }

这个是我写的一个 AuthenticationProvider，只不过我重写了一个类继承了 DaoAuthenticationProvider。

这里我们来看 DaoAuthenticationProvider 类：(这个类里面并没有发现  authenticate 方法，那先从它的父类找)

父类是 AbstractUserDetailsAuthenticationProvider，它也实现了 InitializingBean 接口，也是初始化为一个 Bean。

public Authentication authenticate(Authentication authentication)
            throws AuthenticationException {
        Assert.isInstanceOf(UsernamePasswordAuthenticationToken.class, authentication,
                () -> messages.getMessage(
                        "AbstractUserDetailsAuthenticationProvider.onlySupports",
                        "Only UsernamePasswordAuthenticationToken is supported"));

        // Determine username
        String username = (authentication.getPrincipal() == null) ? "NONE_PROVIDED"
                : authentication.getName();

        boolean cacheWasUsed = true;
        UserDetails user = this.userCache.getUserFromCache(username);

        if (user == null) {
            cacheWasUsed = false;

            try {
                user = retrieveUser(username,
                        (UsernamePasswordAuthenticationToken) authentication);
            }
            catch (UsernameNotFoundException notFound) {
                logger.debug("User '" + username + "' not found");

                if (hideUserNotFoundExceptions) {
                    throw new BadCredentialsException(messages.getMessage(
                            "AbstractUserDetailsAuthenticationProvider.badCredentials",
                            "Bad credentials"));
                }
                else {
                    throw notFound;
                }
            }

            Assert.notNull(user,
                    "retrieveUser returned null - a violation of the interface contract");
        }

        try {
            preAuthenticationChecks.check(user);
            additionalAuthenticationChecks(user,
                    (UsernamePasswordAuthenticationToken) authentication);
        }
        catch (AuthenticationException exception) {
            if (cacheWasUsed) {
                // There was a problem, so try again after checking
                // we're using latest data (i.e. not from the cache)
                cacheWasUsed = false;
                user = retrieveUser(username,
                        (UsernamePasswordAuthenticationToken) authentication);
                preAuthenticationChecks.check(user);
                additionalAuthenticationChecks(user,
                        (UsernamePasswordAuthenticationToken) authentication);
            }
            else {
                throw exception;
            }
        }

        postAuthenticationChecks.check(user);

        if (!cacheWasUsed) {
            this.userCache.putUserInCache(user);
        }

        Object principalToReturn = user;

        if (forcePrincipalAsString) {
            principalToReturn = user.getUsername();
        }

        return createSuccessAuthentication(principalToReturn, authentication, user);
    }

在这段代码中可以知道：如果 authentication.getPrincipal() 为空的话，username 将会为 NONE_PROVIDED。

不为空的话将会得到 authentication.getPrincipal()，也就是用户名，只是这种类型不是 String 类型，但可以强制转换。

代码中是 authentication.getName()，这种和上面基本一样，只不过该类型是 String 类型的。

然后定义一个 user，先尝试从缓存中获取 user，没获取到的话就通过 retrieveUser 获取。

该类中 retrieveUser 是一个抽象方法，我们现在来看 DaoAuthenticationProvider 类里的方法。

protected final UserDetails retrieveUser(String username,
            UsernamePasswordAuthenticationToken authentication)
            throws AuthenticationException {
        prepareTimingAttackProtection();
        try {
            UserDetails loadedUser = this.getUserDetailsService().loadUserByUsername(username);
            if (loadedUser == null) {
                throw new InternalAuthenticationServiceException(
                        "UserDetailsService returned null, which is an interface contract violation");
            }
            return loadedUser;
        }
        catch (UsernameNotFoundException ex) {
            mitigateAgainstTimingAttack(authentication);
            throw ex;
        }
        catch (InternalAuthenticationServiceException ex) {
            throw ex;
        }
        catch (Exception ex) {
            throw new InternalAuthenticationServiceException(ex.getMessage(), ex);
        }
    }

从代码中可以看到是通过我们之前写的 UserDetailsService 方法获取用户。

接下来我们看后面的代码，这部分异常代码我们等会再看。

try {
            preAuthenticationChecks.check(user);
            additionalAuthenticationChecks(user,
                    (UsernamePasswordAuthenticationToken) authentication);
        }

这两句代码是对用户进行检查的，第一行代码调用的其实是这部分的：

private class DefaultPreAuthenticationChecks implements UserDetailsChecker {
        public void check(UserDetails user) {
            if (!user.isAccountNonLocked()) {
                logger.debug("User account is locked");

                throw new LockedException(messages.getMessage(
                        "AbstractUserDetailsAuthenticationProvider.locked",
                        "User account is locked"));
            }

            if (!user.isEnabled()) {
                logger.debug("User account is disabled");

                throw new DisabledException(messages.getMessage(
                        "AbstractUserDetailsAuthenticationProvider.disabled",
                        "User is disabled"));
            }

            if (!user.isAccountNonExpired()) {
                logger.debug("User account is expired");

                throw new AccountExpiredException(messages.getMessage(
                        "AbstractUserDetailsAuthenticationProvider.expired",
                        "User account has expired"));
            }
        }
    }

可以看到并不是检查密码的，只是对用户状态进行检查。那么我们不管它了，看下一行代码：

@SuppressWarnings("deprecation")
    protected void additionalAuthenticationChecks(UserDetails userDetails,
            UsernamePasswordAuthenticationToken authentication)
            throws AuthenticationException {
        if (authentication.getCredentials() == null) {
            logger.debug("Authentication failed: no credentials provided");

            throw new BadCredentialsException(messages.getMessage(
                    "AbstractUserDetailsAuthenticationProvider.badCredentials",
                    "Bad credentials"));
        }

        String presentedPassword = authentication.getCredentials().toString();

        if (!passwordEncoder.matches(presentedPassword, userDetails.getPassword())) {
            logger.debug("Authentication failed: password does not match stored value");

            throw new BadCredentialsException(messages.getMessage(
                    "AbstractUserDetailsAuthenticationProvider.badCredentials",
                    "Bad credentials"));
        }
    }

这里有个获取密码的操作：authentication.getCredentials()。

然后如果密码不为空的话就通过 passwordEncoder.matches(presentedPassword, userDetails.getPassword() 检查是否匹配。

如果匹配成功的话，嗯，这部分结束了，我们回到 AbstractUserDetailsAuthenticationProvider 类里的 authenticate 方法。

return createSuccessAuthentication(principalToReturn, authentication, user);

它会返回一个创建成功认证方法的返回值。这里我们就不管了。

现在我们先回到AbstractUserDetailsAuthenticationProvider 类的错误处理上：

try {
                user = retrieveUser(username,
                        (UsernamePasswordAuthenticationToken) authentication);
            }
            catch (UsernameNotFoundException notFound) {
                logger.debug("User '" + username + "' not found");

                if (hideUserNotFoundExceptions) {
                    throw new BadCredentialsException(messages.getMessage(
                            "AbstractUserDetailsAuthenticationProvider.badCredentials",
                            "Bad credentials"));
                }
                else {
                    throw notFound;
                }
            }

这个是用户找不到引起的错误，我们看下 messages.getMessage()：

    public String getMessage(String code, String defaultMessage) {
        String msg = this.messageSource.getMessage(code, null, defaultMessage, getDefaultLocale());
        return (msg != null ? msg : "");
    }

再来看下这个里面的 getMessage()：

它是一个接口类里的方法：根据 code 返回 messageSource 里的字符串，如果不存在这个 code，就返回 defaultMessage。

既然是个接口类，那我们看下它的实现类，回到 messageSource，查看一下它：

public class SpringSecurityMessageSource extends ResourceBundleMessageSource {
    // ~ Constructors
    // ===================================================================================================

    public SpringSecurityMessageSource() {
        setBasename("org.springframework.security.messages");
    }

    // ~ Methods
    // ========================================================================================================

    public static MessageSourceAccessor getAccessor() {
        return new MessageSourceAccessor(new SpringSecurityMessageSource());
    }
}

原来是从这个路径里找数据源。

其他的错误处理也是一样，这里就省略了。那我们如何获取错误信息呢？

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        // TODO Auto-generated method stub
        http
        .authorizeRequests()
        .anyRequest().permitAll()
        .and()
        .formLogin().loginPage("/signin")
        .usernameParameter("username")
        .passwordParameter("password")
        .loginProcessingUrl("/signin")
        .failureHandler(authenticationFailureHandler)
        .and()
        .csrf().disable();

看到那个 failureHandler 没，这个是登录失败处理器，这里加上只是看一下里面源码：AbstractAuthenticationFilterConfigurer

    /**
     * Specifies the {@link AuthenticationFailureHandler} to use when authentication
     * fails. The default is redirecting to "/login?error" using
     * {@link SimpleUrlAuthenticationFailureHandler}
     *
     * @param authenticationFailureHandler the {@link AuthenticationFailureHandler} to use
     * when authentication fails.
     * @return the {@link FormLoginConfigurer} for additional customization
     */
    public final T failureHandler(
            AuthenticationFailureHandler authenticationFailureHandler) {
        this.failureUrl = null;
        this.failureHandler = authenticationFailureHandler;
        return getSelf();
    }

从注释中可以看出默认的失败处理器是 SimpleUrlAuthenticationFailureHandler：

    public void onAuthenticationFailure(HttpServletRequest request,
            HttpServletResponse response, AuthenticationException exception)
            throws IOException, ServletException {

        if (defaultFailureUrl == null) {
            logger.debug("No failure URL set, sending 401 Unauthorized error");

            response.sendError(HttpStatus.UNAUTHORIZED.value(),
                HttpStatus.UNAUTHORIZED.getReasonPhrase());
        }
        else {
            saveException(request, exception);

            if (forwardToDestination) {
                logger.debug("Forwarding to " + defaultFailureUrl);

                request.getRequestDispatcher(defaultFailureUrl)
                        .forward(request, response);
            }
            else {
                logger.debug("Redirecting to " + defaultFailureUrl);
                redirectStrategy.sendRedirect(request, response, defaultFailureUrl);
            }
        }
    }

因为默认的 defaultFailureUrl 为 /login?error，从 AbstractAuthenticationFilterConfigurer 类里可以看出来。

登录失败后，会调用 saveException(request, exception); 保存错误信息。

protected final void saveException(HttpServletRequest request,
            AuthenticationException exception) {
        if (forwardToDestination) {
            request.setAttribute(WebAttributes.AUTHENTICATION_EXCEPTION, exception);
        }
        else {
            HttpSession session = request.getSession(false);

            if (session != null || allowSessionCreation) {
                request.getSession().setAttribute(WebAttributes.AUTHENTICATION_EXCEPTION,
                        exception);
            }
        }
    }

由于该类中 forwardToDestination 为 false，它将执行 else 里的语句。

将错误信息保存到会话的 WebAttributes.AUTHENTICATION_EXCEPTION 属性中：

public static final String AUTHENTICATION_EXCEPTION = "SPRING_SECURITY_LAST_EXCEPTION";

所有我们可以通过会话的这个属性来获取错误信息。(thymeleaf)

(注意：signin.html 不能放在 static 目录下，不然获取不到错误信息。)

<p th:if="${param.error}" th:text="${session?.SPRING_SECURITY_LAST_EXCEPTION?.message}" ></p>

好啦，都介绍完了，可以看下我的 CustomAuthenticationProvider：

package security.config;

import org.springframework.security.authentication.BadCredentialsException;
import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
import org.springframework.security.authentication.dao.DaoAuthenticationProvider;
import org.springframework.security.core.Authentication;
import org.springframework.security.core.AuthenticationException;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.security.core.userdetails.UsernameNotFoundException;
import org.springframework.util.Assert;

public class CustomAuthenticationProvider extends DaoAuthenticationProvider {

    @Override
    protected void additionalAuthenticationChecks(UserDetails userDetails,
            UsernamePasswordAuthenticationToken authentication) throws AuthenticationException {
        // TODO Auto-generated method stub

        String presentedPassword = authentication.getCredentials().toString();
        if (!getPasswordEncoder().matches(presentedPassword, userDetails.getPassword())) {
            logger.debug("Authentication failed: password does not match stored value");

            throw new BadCredentialsException(messages.getMessage(
                    "UNameOrPwdIsError","Username or Password is not correct"));
        }
    }

    @Override
    public Authentication authenticate(Authentication authentication) throws AuthenticationException {
        // TODO Auto-generated method stub
        Assert.isInstanceOf(UsernamePasswordAuthenticationToken.class, authentication,
                () -> messages.getMessage(
                        "AbstractUserDetailsAuthenticationProvider.onlySupports",
                        "Only UsernamePasswordAuthenticationToken is supported"));

        if("".equals(authentication.getPrincipal())) {
            throw new BadCredentialsException(messages.getMessage(
                    "UsernameIsNull","Username cannot be empty"));
        }
        if("".equals(authentication.getCredentials())) {
            throw new BadCredentialsException(messages.getMessage(
                    "PasswordIsNull","Password cannot be empty"));
        }

        String username = (String) authentication.getPrincipal();
        boolean cacheWasUsed = true;
        UserDetails user = this.getUserCache().getUserFromCache(username);
        if (user == null) {
            cacheWasUsed = false;
            try {
                user = retrieveUser(username,
                        (UsernamePasswordAuthenticationToken) authentication);
            }
            catch (UsernameNotFoundException notFound) {
                logger.debug("User '" + username + "' not found");

                if (hideUserNotFoundExceptions) {
                    throw new BadCredentialsException(messages.getMessage(
                            "UNameOrPwdIsError","Username or Password is not correct"));
                }
                else {
                    throw notFound;
                }
            }
            Assert.notNull(user,
                    "retrieveUser returned null - a violation of the interface contract");
        }
        try {
            getPreAuthenticationChecks().check(user);
            additionalAuthenticationChecks(user,
                    (UsernamePasswordAuthenticationToken) authentication);
        }
        catch (AuthenticationException exception) {
            if (cacheWasUsed) {
                cacheWasUsed = false;
                user = retrieveUser(username,
                        (UsernamePasswordAuthenticationToken) authentication);
                getPreAuthenticationChecks().check(user);
                additionalAuthenticationChecks(user,
                        (UsernamePasswordAuthenticationToken) authentication);
            }
            else {
                throw exception;
            }
        }

        getPostAuthenticationChecks().check(user);

        if (!cacheWasUsed) {
            this.getUserCache().putUserInCache(user);
        }

        Object principalToReturn = user;

        if (isForcePrincipalAsString()) {
            principalToReturn = user.getUsername();
        }

        return createSuccessAuthentication(principalToReturn, authentication, user);
    }

}

这里值得注意的是 "".equals(authentication.getPrincipal())，"".equals(authentication.getCredentials())

因为如果按照那个 AbstractUserDetailsAuthenticationProvider 类来写的话，发现这一步永不为 null。

我通过加入代码 System.out.println(username);  才知道的，应该是个坑吧。

项目代码可供大家参考：

链接：https://pan.baidu.com/s/13fc6P9NV49aRRBctr3MjNQ
提取码：4qgu